1. Field of the Invention
This invention relates to a copying machine for microfilm.
2. Description of the Prior Art
In a conventional copying machine for microfilm, the image of a picture formed on a microfilm is enlarged by a lens and the image thus enlarged is projected onto a photo-sensitive material through a slit member at an image focusing point thereof. A typical example of such a conventional copying machine for microfilm has been disclosed by the specification of Japanese Patent Application Publication No. 396/1965.
A picture is formed only on one surface of a microfilm. Therefore, when the microfilm is set on the copying machine so that the lens is correctly focused on that surface, the conventional copying machine operates satisfactorily. However, when the microfilm is turned over and set on the copying machine, the lens cannot be correctly focused on the picture. In order to force the lens to focus on the picture in this case, sometimes a manual focusing operation is employed. However, manual focusing is considerably delicate and difficult.